1. Field of the Invention
This invention relates generally to lighting fixtures for illuminating an area containing ignitable materials. More particularly, this invention relates to an improved battery backed-up, explosion proof lighting fixture that will generate light in the event of a loss of the external power.
2. Description of the Prior Art
Regulation and codes dictate the type of lighting equipment that can be used in areas or environments containing ignitable material in attempts to prevent lighting fixtures from causing the ignitable materials to explode. For example, a spark generated by the lighting fixture could cause the material to explode. Therefore, the regulations are primarily directed to the housing of the fixture containing the light source.
Many types of lighting fixtures could be useful in the ignitable environments including, for example, main lighting fixture, exit lighting fixture, and safety lighting fixture. Main lighting fixtures are used to illuminate the entire area. Typically, self-powering exit lighting fixtures and safety lighting fixtures are designed to function in the event of a power failure. Exit lighting fixtures that emit sufficient light to identify the location of exits are positioned at the appropriate locations. Safety lighting fixtures function similarly to exit lighting fixtures, but typically emit more light than exit lighting fixtures. Since both the exit and safety lighting fixtures are used during power outages, most utilize batteries or some other self powering mechanism.
Many manufacturers market battery backed-up, explosion proof exit and safety lighting fixtures (hereinafter referred to as "prior art fixtures"). These lighting fixtures have some deficiencies most of which are associated with the designs and configurations of the these lighting fixtures. Most manufacturers manufacture two types of units: the single light unit and the multilight unit. The problems associated with the single light units are found in the multilight units as well. However, there are unique deficiencies associated with the multilight units. The following discussion on the deficiencies of the prior art fixtures is directed to both single unit safety and exit lighting fixtures unless otherwise specified.
One problem with the design of the prior art fixture design is that the battery is located external to the housing containing the light source. A typical fixture includes a lighting housing connected to a bracket that is mounted to a battery box. The battery box is designed to be permanently mounted to the wall or the support structure and typically includes several bolts or other types of locking mechanisms to maintain any electronics and the batteries therein. The entire fixture is usually very heavy and cumbersome to install.
Due to permanent installations and the location of the batteries of the prior art lighting fixtures, maintenance and replacement of the fixtures are sometimes time consuming and costly. For example, in order to replace or test the battery, the entire fixture, including the lighting housing, the bracket, and the battery box, should be removed in order to isolate the electronics from the ignitable material, and thus, maintain a fully explosion proof status. However, in practice, when repair or replacement of the electronics or batteries is necessary, the bolts or other locking mechanisms are removed from the battery box, thus exposing the ignitable material to the electronics and batteries. Therefore, the entire heavy lighting fixture must be removed to avoid a potential explosion during repair or maintenance.
Another problem with the prior art lighting fixtures is that the fixtures are permanently affixed to a wall or support structure end cannot be removed to illuminate other areas unreachable by the light from the permanently mounted fixtures. In some instances, it may be necessary to illuminate these other areas, for example, different passage ways may need to be illuminated during the evacuation of a building.
There is at least one problem that is exclusively associated with the multilight units, where at least two lamps are connected to the single remote battery. When the battery fails, so do all the lights attached to that battery.
Yet another problem with the prior art lighting fixture is that the lighting fixture is only illuminated when there is a loss of external power. In some instance, it is desirable to have safety lighting fixtures that are illuminated at all times.
Finally, the prior art light fixtures utilize incandescent bulbs as light sources. Incandescent bulbs are not as efficient as, for example, flourescent bulbs. Incandescent bulbs generally require quite a bit of power for illumination, which consequently requires a large battery. The life time of the incandescent bulb is not as long as flourescent, thus, requiring more frequent replacements.
Therefore, it is an object of this invention to provide a self contained, explosion proof lighting fixture to illuminate an area containing ignitable materials.
It is another object of the present invention to provide a multilight, self-contained, explosion proof lighting fixture, wherein the failure of one lighting fixture or battery will not cause the remaining fixture light to fail.
It is another object of the present invention to provide a portable exit or safety lighting fixture.
It is yet another object of the present invention to provide exit and safety lighting fixtures that are easily maintained and replaced.
It is another object of the present invention to provide an efficient, light weight exit or safety lighting fixture.